import java.io.*;
 
public class URLEncoder {
  public static String URLencode(String s)
  {
  	if (s!=null) {
  		StringBuffer tmp = new StringBuffer();
  		int i=0;
  		try {
  			while (true) {
  				int b = (int)s.charAt(i++);
  				if ((b>=0x30 && b<=0x39) || (b>=0x41 && b<=0x5A) || (b>=0x61 && b<=0x7A)) {
  					tmp.append((char)b);
  				}
  				else {
  					tmp.append("%");
  					if (b <= 0xf) tmp.append("0");
  					tmp.append(Integer.toHexString(b));
  				}
  			}
  		}
  		catch (Exception e) {}
  		return tmp.toString();
  	}
  	return null;
  }

}
